Gstumbler tells all

The third party commissioned by Google to review the software used in its Street View WiFi cars has completed its report, called Source Code Analysis of ‘Gstumbler’.  I will resist commenting on the name, since Google did the right thing in publishing the report:  there will no longer be any ambiguity about what was being collected. 

As we have discussed over the last week, two issues are of importance – collection of device identity data, and collection of payload data.  One thing I like about te report is that it has a begins with a a number of technical “descriptions and definitions”.  For example, in paragraph 7 it explains enveloping:

“Each packet is comprised of a packet header which contains network administrative information and the addressing information (or “envelope” information) necessary to transmit the data packet from one device to another along the path to its final destination.  Each packet also contains a “payload” which is a fragment of the “content” of the communication or data transmission sent or received over the internet…”

It explains that in 802.11 packets are encapsulated in frames, describes the types of frames and presents the standard diagram showing how a frame is structured.

Readers should understand that when network encryption is turned on, it is only the Frame Body (Payload) of data frames that is encrypted.

In paragraph 19, the report provides an overview of its findings:

“While running in memory, the program parses frame header information, such as frame type, MAC addresses, and other network administrative data from each of the captured frames.  The parsing separates the information into discreet fields for easier analysis… All available MAC addresses contained in a frame are also parsed.  All of this parsed header information is written to disk for frames transmitted over both encrypted and unencrypted wireless networks [emphasis mine – Kim].”

In paragraph 20, the report explains that the software discards the content of encrypted bodies (which of course it can't analyse anyway) whereas unencrypted bodies are also written to disk.  I have not discussed the issue of collecting the frame bodies in these pages – there is no need to do so since it is intuitively easy for people to understand what it means to collect payloads.

In paragraph 22 the report concludes that “all wireless frame data was recorded except for the bodies of 802.11 Data frames from encypted networks.” 

All device identifiers were recorded

As a result, there is no longer any question.  The MAC addresses of all the WiFi laptops and phones in the homes, businesses, enterprises and government buildings were recorded by the driveby mapping cars, as were the wireless access points, and this regardless of the use of encryption. 

My one quibble with the otherwise excellent report is that it calls the MAC addresses “network administrative data”.  In fact they are the device identifiers of the network devices – both of the network access point and the devices connecting to that access point – phones and laptops.

It is also worth, given some of the previous conversations about supposed “broadcasting”, drawing attention to paragraph 26, which explains,

“Kismet captures wireless frames using wireless network interface cards set to monitoring mode.  The use of monitoring mode means that Kismet directs the wireless hardware to listen for and process all wireless traffic regardless of its intended destination… Through the use of passive packet sniffing, Kismet can also detect the existence of netwrks with non-broadcast SSIDs, and will capture, parse, and record data from such networks.”


It is all Metcalfe’s fault

Christian Huitema, author of IPv6: The New Internet Protocol (2nd Edition) and one of the leading architects of IPV6, had this to tell us:

It is all Metcalfe’s fault. There is no real functional need to have the MAC addresses unique worldwide, but it certainly is very convenient. If they weren’t unique, we would have to add a protocol to detect address collisions and somehow resolve them. That’s hard enough for static attachments, but becomes really hairy when dealing with a high mobility environment, e.g. Wi-Fi enabled smart phones that connect to different base stations as we roam the corridors of the buildings. Making MAC addresses unique really simplified the design, but it did not actually spare the need for detecting duplicates. Simply, we treat that as an error, to be corrected by network management systems.

The initial design of IPv6 called for embedding the MAC addresses in the IPv6 address. A host IPv6 address would be built as the combination of a 64 bit network prefix and a MAC address expanded to 64 bits. Our Windows Networking team saw that as a serious issue, and we proposed an alternative design in which host pick randomized “host identifiers”, that vary each time they connect to a new network. That’s what you get by default in Vista and in Windows 7, although managers can still force the old “standard compliant” behavior and request that the identifier be set to the MAC address. I believe that most other operating systems just build IPv6 address using the MAC address.

The worldwide database of MAC addresses would be even more valuable if we had kept using MAC addresses in IPv6 addresses. In fact, it may be valuable enough as most smart phone stacks still do that. Web sites and other services see the incoming IPv6 address, extract the database, and, voila, precise identification of the caller identity, location, you name it. Picture Bill Joy’s smirk, “told you so.”

Your understanding of the Wi-Fi protocol is correct. Only the payload is encrypted, not the MAC header.  The 802.11 MAC header actually differs from the Ethernet MAC header and carries up to 4 MAC addresses: the immediate wireless sender, the intended wireless receiver, the original source and the final destination. The final destination is used for example when sending a packet from one mobile to another through a base station. Depending of scenarios, headers carry 2, 3 or 4 Mac addresses – addresses are not repeated, for example, when the original source is the same as the wireless sender, or when the intended destination is the same as the wireless destination.

The MAC header itself was not protected, at least not initially. This can lead to possible spoofing of control frames, e.g. disconnection requests. 802.11 in 2009 defined 802.11w to add protection to management frames, but this is essentially an anti-spoofing standard. It may optionally encrypt some management data, but it cannot encrypt the wireless MAC addresses.

These are very important points.  The problem of moving between multiple base stations in the same network would make MAC encryption a non-starter unless we took a heavy dependence on communication between the base stations, introducing the reliability concerns that implies.  In other words, the problem is not quite as simple as Hal Berenson suggested here. 

Yet Christian has found an elegant and simple alternative.  I really take my hat off to him  for having been visionary enough – and sufficiently tuned into identity issues – to generate, by default, a different IPV6 MAC address for each network a device connects to.   I remember Christian discussing the issues and telling me he saw this as a possibility but had no idea until now he had succeeded in getting it out the door and onto millions of devices. 

This approach solves the linking problem I've been describing, because the MAC address snooped in your home would be different from the MAC address generated should you go to your workplace or attend a conference.   In essence, Christian has made the IPV6 MAC addresses properly unidirectional, in the sense of being contextually specific identifiers, and in this sense has brought IP into conformance with the Fourth Law of Identity.

Although this benefit only kicks in as the infrastructure evolves to IPV6, it establishes the fact that the end-state we will reach is one in which WiFi snooping won't provide the ability to link people across contexts as various commercial interests are currently attempting to do. 

It also, in my view, gives me confidence that regulation preventing collection and linking of MAC addresses would be totally consistent with the direction technological evolution will take us in anyway.   This is really key, since we never want regulation to tell technologists what to do – only, in protecting the public, to tell us what not to do

There is, however, a macabre side to Christian's comment. 

Implementations of IPV6 that do always include a persistent and unchanging MAC address in their IPV6 address need to be fixed.  They make the problem of unique identification across contexts worse, not better, since the MAC address moves up the stack to the IP layer…   We need the people responsible for these implementations to understand the issues and provide privacy-friendly alternatives just as Christian did.  Looks like there is more work to be done… 

“We could all be wrong about the way 802.11 works…”

I received a comment from a reader who plays an important role in the network protection industry which reads:

“I was a bit surprised by you going on about Google getting the MAC addresses of devices in people's home. I asked a few other security folks, and none of us could figure out why you thought that Google had these addresses.

“Of course, we could all be wrong about the way that 802.11 works, but I would have thought that the only way that the Google Car could see anything other than the MAC address of the WAP would be if both:
– the car quickly impersonated the WAP by forging its SSID
– the computers in the house tried to re-attach to the device forging the SSID Is this the scenario you think happened? If so, where did you see this? If not, what am I am misunderstanding about Wifi where just receiving signals without looking like a WAP allows me to see any MACs other than those of WAPs?

“I look forward to hearing more on this, even if my understanding of WiFi (and that of the folks I asked) is wrong.”

Unfortunately, the assumptions made by my reader, even though supported by other experts, are wrong. 

Few technologies are more ubiquitous or foundational than 802.11 wireless (WiFi).  The security experts in this domain understand perfectly its security characteristics relative to protection of the data payload.  But in the past the device identity aspects of the system have not been on the front burner.  No wonder.  I imagine that anyone worried about some information agency accumulating all the MAC addresses in the world and mapping them to the houses people live in would have been sent off to the looney bin a few years ago: “Sure, and pigs might fall from the sky and crush us too!  Now let's get this thing deployed!”

Of course I come at this from a different direction since I'm an “identity guy” and the identity of the devices is something I have had to understand and deal with.  But given the importance of the discussion I turned to two colleagues in other disciplines to verify that my own understanding remains correct despite the evolution of the standards.  One is Khaja Ahmed, an expert in network security; the other is Christian Huitema, an expert in all aspects of networking.

I'll share Christian's comments in a separate post.  Khaja responded:   

“Yes, the senders MAC address is in the clear. Of course the recipients (WiFi access point) MAC address has to be in the clear so it knows that the packet is intended for it. The client’s MAC address is needed so the WiFi access point knows which session key and state to use to process the frame. Just as the SA in IPsec cannot be identified without the IP address of the sender.

“One more point re the four fields you are talking about… There are 3 or 4 MAC addresses in each 802.11 frame depending on who is sending the packet to who on whose behalf.

“The sender and destination addresses are always there, so that’s two. The third address is typically the Base Station Identifier. In cases where the packets are being relayed by some other part of the infrastructure there may be addresses of some intermediate transmitter and receiver. That gives you the 4 addresses. The MAC address of the original sender / client is just one field.


The core of the matter at hand

We've explored many of the basic issues of WiFi snooping.  I would now like to go directly to the core of the matter: why do large centralized databases of MAC addresses linked to our street addresses have really serious consequences for peoples’ privacy?  I'd like to approach this through an example:

Consider the case of someone attending a conference at which people are using laptops and phones over a wireless network.  We picture the devices within range of a given attendee in Figure 1:

The green dot represents the WiFi access point through which conference attendees gain access to the Internet.  For now, let's assume this is a permanent WiFi network.  Let's therefore assume its MAC address and location are present within the linking database that also contains our residential MAC to street address mapping.

Now suppose one or more people at the conference have opted into a geo-location service that makes use of the database.  And let's assume that the way this service works is to listen for nearby MAC addresses (all the little circles in the figure) and submit them to the geo-location system for analysis.

The geo-location system will learn that the opted-in user (let's call him Red) is near the given WiFi point, and thus will know Red is at a given location.  If the geo-location system is also capable of searching the web (as one would expect that Google's could), it will also be able to infer that Red is in a given hotel, and that the hotel is hosting a conference C on the date in question. 

If Red stays in the same location for some time, and is surrounded by a number of other people who are in the same location (discernable because their MAC addresses continue to be near by), the smart service will be able to infer that Red is attending conference C being held in the hotel. 

So far, there's nothing wrong with this, since Red has opted in to the geo-location service, and presumably been told that's how it works.

However, note that the geo-location system also learns about the MAC addresses of all the attendees within range who have NOT opted into the system (Green).  And if they remain within range over time, it can also deduce that they too are present at conference C.  Further, it can look up their MAC addresses in the database to discover their street addresses.  This in turn can be used to make many inferences about who the attendees at the conference are, since a lot of information is keyed to their street addresses.  That can itself become further profile information.

Opting out doesn't help

The problem here is this:  The geo-location system is perfectly capable of tracking your location and associating it with your home street address whether you opt in or not.  Home address is a key to many aspects of your identity.  Presto – you have linked many aspects of your identity to your location, and this becomes intellectual property that the geo-location can service sell and benefit from in a myriad of ways.

Is this the way any particular geo-location services would actually work?  I have no idea.  But that's not the point.  The point is that this is the capability one enables by building the giant central database of laptop and phone MAC addresses linked to street addresses.

Commercial interest will naturally tend towards maximal use of these capabilities and the information at hand. 

That is why we need to fully understand the implications of wirelesstapping on a massive scale and figure out if and where we want to draw the line.  How does the collection of MAC addresses using WiFi trucks relate to the regulations involving data collection, proportionality and consent?  Are there limits on the usage of this data? 

One thing for sure.  Breaking the Fourth Law, and turning a unidirectional identifier into a universal identifier is like the story of the Sorcerer's Apprentice.  All the brooms have started dancing.  I wonder if Mickey will get out of this one?


More input and points of view

Dave Nikolejsin, CIO of British Columbia and a man who sees identity as the key to efficient government, writes:

“I agree with your comments and focus on the MAC layer data collection going on with Google. One observation I would have re all the “other” similar type activity would be that no others have Google’s resources and thus no others are doing systematic sweep of the western world on such a data gathering mission. As we all know the value of data increases in an N-squared manner and the “N” once Google is done will be a big number.”

Dave goes on to compare wirelesstapping with Facebook's privacy problems and makes what I think is a very insightful comment:

At least (for all its warts) we actually willingly give our info to Facebook!

Heavy duty SOA architect Gunnar Peterson (an expert on Service-Oriented Security) condenses our discussion to date and comes out strongly in favor of the arguments I've been making with regards to the wirelesstapping of MAC addresses: 

Google's Macondo Street View team cannot seem to get the right combination of top kill or cap to fit on its MAC spillage. Your MAC is not like a house number (which everyone knows and are used for many purposes), MAC address is scoped to one use. There's no harm in collecting MACs, the hell you say, there's a number of evil emergent cocktails that can come out of this. Its not so much the MAC itself, its the association of the MAC and the gelocation and time – combining something unique like MAC with geolocation.

This looked like a rogue team (or as Google put it last week a “rogue software engineer“) until this shocking announcement that Google is patenting (emphasis added) – “The invention pertains to location approximation of devices, e.g., wireless access points and client devices in a wireless network.”

It seems pretty obvious that any number of permutations of problems  will result by combining private client data and geolocation. Maybe Google books should scan a copy of J.C. Cannon's book “Privacy: What Developers and IT Professionals Should Know” and Stefan Brands Primer on User Identification.  In both works you see the risks of promiscuously mixing identification cocktails and the unexpected leakages that result. In addition, what does benefit to the user who is being spied upon does all this spying create…?

[More here]

It's true that J.C. and Stefan both do a great job of helping explain the issues at play here, and I advise people who want to understand the issues better to check out their work.

Hal Berenson got back to me after my response to him, saying,

One thing I would suggest is that you write language attempting to ban what you want to ban and let the rest of us poke holes in it  – meaning, show all the legitimate scenarios you would make illegal or accidental criminals you would create… 🙂

I have total sympathy with this concern of course.  We want the minimum intervention necessary.  But our society has come to realize there are many instances where consumers and citizens need be protected in various ways.  In introducing these protections, lawmakers had to deal with exactly the same difficult concerns about balancing rights.  The good news here:  our legal system seems to handle this just fine.  In fact, that's what it is about.   So I will leave the crafting of the appropriate disincentives to professionals.

Ted Howard, who has broad experience including in the Games industry, commented,

Regarding the issues of Google's collection of MAC addresses and wireless SSIDs:

“If I leave my blinds open so that I can get sun into my home, that means I have no problem with anyone walking past my house pausing to watch me in my home. When I talk with a friend while walking in the park, that means I cannot be bothered by a stranger walking alongside us listening to every word. In both cases, am I “publicly broadcasting” something or is the broadcast just a side effect of my activities? The analogy should be clear.


“Do a survey to see how many wireless router owners understand what MAC and SSID are. I suspect that very few (< 5%) people know. If they don't know what these are, then how can anyone claim that these people have been intentionally publicly broadcasting these with an understanding that the broadcast has become publicly-available knowledge? Government regulation exists to, among other reasons, protect the public when the public needs protection and would otherwise be unprotected. This seems to me like a good case for protecting the truly ignorant public.

Journalist Mary Branscombe comments:

For me there are 3 big questions.

  1. How much info did or could someone capture; and by the way Google is in the data capture and data mining/machine learning business and that data *has* been used because if they didn't know it was there they didn't know they had to exclude it.
  2. How personally identifiable or anonymised that information is (i don't think my phone has a bunch of captured MAC addresses and if it does I don't think it has any pii about them but I may be wrong.
  3. How much people care. What is public or private about my SSID or about my MAC address? (I honestly don't know is how much you can find out about me from my MAC address but I'm assuming not much; if I'm wrong that's a data point! I know in 2007 Skyhook told me they were confident they had privacy cracked but they would and they're not the only people and they're the good guys…)

Location services is a *huge* business and people are oversharing location information for trivial rewards (see Foursquare). 8000 apps use Skyhook location data. It's Facebook with co-ordinates. I don't think we can not do this – but I think we can regulate and do it more safely.

In answer to Mary's question two, systems like the Street View Wifi system exist to map peoples’ device MAC addresses to their residential address, as described in the Google patent.  Her point about big business is a BIG POINT.  But to me it just increases the urgency to give people the geo-location capabilities they want without creating a privacy chernoble that will explode down the line.

Jan and Susan Huffman write,

“Standing naked in my front yard is like broadcasting my MAC address.  If I don’t want people to look at me naked in my front yard, I wear clothes. I don’t ask that the law punish those who might take a look through the bushes.

My response:  your MAC address is visible in your wireless packets no matter what you do.  Turning on encryption doesn't help.  So there are no clothes to put on.  The analogy with clothes and bushes therefore just doesn't stand up.  Furthermore, in most neighborhoods, if you spend your time trawling the neighborhood and peeking through bushes you end up with people giving you a pretty hard time…  Maybe that's what's happening here.


There is a fundamental problem here

Joe Mansfield at Peccavi has done a very cogent post where, though he agrees with my concerns, he criticizes me for picking almost exclusively on Google when there are lots of others who have been doing the same thing.  He's right – I have been too narrowly focused. 

Let me be clear:  I have great respect for Google and many of its accomplishments.   I have a disagreement with a particular Google team.

I find the Google Street View team's abuse of identifiers especially worrisome because they have not only been collecting info about WiFi access points, but the MAC addresses of peoples’ personal devices (laptops and phones).  

This bothers me because I see it as dangerous.  It's like going over to visit a neighbor and finding out he's been building a nuclear reactor in his basement. 

 I'm not an expert on the geolocation industry and I have no knowledge of whether this kind of end-user-device-snooping is commonplace.  If it is, then let me know.  Everything I have said about Google applies equally to any similar practitioners. 

But let's get to Peccavi which makes the point better than I do:

I’ve been following Kim Cameron’s increasingly critical analysis of Google’s StreetView WiFi mapping data privacy debacle with some interest of late.

Some background might be in order for those interested in reading where he’s been coming from – start here and work forward. He’s been quite vocal and directed in his criticism and I have been surprised that his focus has been almost entirely on Google rather than on the underlying technical root cause. My initial view on the issue was that it was a stupid over-reaction to something that everyone has been doing for years, and that at least Google were being open about having logged too much data. I’m still of the opinion that the targeting of Google specifically is off base here, although I think Kim is right that there is a fundamental problem here.

Kim is probably the pre-eminent proponent and defender of strong authentication and privacy on the net at the moment. His Laws of Identity should be mandatory reading for anyone working with user data in any sort of context but especially for anyone working with online systems. He’s a hugely influential thought leader for doing the right thing and as a key technical leader within Microsoft he’s doing more than almost anyone else to lay the groundwork for a move away from our current reliance on insecure, privacy leaking methods of authentication. Let’s just say that I’m a fan.

For obvious reasons he has spotted the huge privacy problems associated with the practice of gathering WiFi SSID and MAC addresses and using them to create large scale geo-location databases. There are serious privacy issues here and despite my initial cynicism about this perhaps it’s a good thing that there has been a huge furore over what Google were doing.

Note that there were two issues in play here – the intentional data (the SSID’s, MAC addresses and geo-location info) and the unintentional data (actual user payloads). I’m only going to talk about the intentionally harvested data right now because that is the much trickier problem – few people would argue that having Google (or anyone) logging actual WiFi traffic from their homes is OK.

The problem that I see with Kim’s general position on this and the focus on Google’s activities alone is that he’s not seeing the wood for the trees. The problem of companies or individuals harvesting this data is minor compared to the problem that enables it. The technical standards that we all use to connect wirelessly with the endless array of devices that we all now have in our homes, use at work and carry on our person every day are promiscuous communicators of identifiers that can be easily and extensively misused. Even if Google are prevented by law from doing it, if the standards aren’t changed then someone else will…

I agree with almost every point made except, “The problem of companies or individuals harvesting this data is minor compared to the problem that enables it.”  I would put it differently.  I would say, “There are two problems.  Both are bad.”

We're technologists so we immediately look to technology to prevent abuse.  This is the right instinct for us to have.  But societly can use disincentives too.  I've come to believe that technology must belong to society as a whole.  And we need a combination of  technical solutions and those society can impose.

I actually think I see at least some of the woods as well as the trees.  That is what the Fourth Law is all about.  Of course I want to change the underlying technology as fast as we can. 

But I don't think that will happen unless there is a MUCH greater understanding of the issues, and I've been trying with this set of posts to get them onto the table.    

[More Peccavi here.]


How to prevent wirelesstapping

Responding to “What harm can possibly come from a MAC address“, Hal Berenson writes:

“The real problem here is technological not legal. You could ban collecting SSIDs and MAC addresses and why would it matter? Your sexual predator scenario wouldn’t be prevented (as (s)he is already committing a far more heinous crime it just isn’t going to deter them). The real problem is that WIFI (a) still doesn’t encrypt properly and (b) nearly all public hotspots avoid encryption altogether. I’ll almost leave (b) alone because it is so obvious, yet despite that we have companies like AT&T pushing us (by eliminating unlimited data plans) to use hotspots rather than their (better) protected 3G access.

“Sure my iPad connects nicely via WIFI when I’m in the United Red Carpet Club, but it also leaves much of my communications easily intercepted (3G may be vulnerable, but it does take some expertise and special equipment to set up my own cell). But what the *&#$#&*^$ is going on with encrypted WIFI not encrypting the MAC addresses? If something needs to be exposed it should be a locally unique address, not a globally unique one! I seem to recall that when I first looked at cryptography in the early 70s I read articles about how traffic analysis on encrypted data was nearly as useful as being able to decrypt the data itself. There were all kinds of examples of tracking troop movements, launch orders, etc. using traffic analysis. It is almost 40 years later and we still haven’t learned our lesson.”

I assume Hal is using “*&#$#&*^$” as a form of encryption.  Anyway, I totally agree with the technical points being made.  WIreless networks used the static MAC concept they inherited from wired systems in order to facilitate interoperability with them.  Designers didn't think the fact that the MAC addresses would be visible to eavesdroppers would be very important – the payload was all they cared about.   As I said in the Fourth Law of Identity:

Bluetooth and other wireless technologies have not so far conformed to the fourth law. They use public beacons for private entities.

I'd love to figure out how we would get agreement on “fixing” the wireless infrastructure.  But one thing is for sure:  it is really hard and would take a while!  I don't think, in the meantime, we should simply allow our private space to be invaded.  Just because technology allows theft of the identifiers doesn't mean society should.

Similarly, in reference to the predator scenario, the fact that laws don't prevent crime has never meant there shouldn't be laws.  Regulation of “wirelesstapping” would make the emergence of this new kind of crime less likely.


MAC addresses will be used to reveal where you live

Conor has responded to my comments on why house numbers don't make a good metaphor for MAC addresses.

He writes that when I characterized house number as a “universal identifier”,

[Kim's argument] “confuses house address with house number. A house number is not able to be used as a universal identifier (I presume that there are many houses out there with the number 15, even in the same town, many times even on the same street in the same zip code (where the only difference is the N.W. and S.E. on the end of the street name).

“Like SSIDs and MAC addresses, the house number is only usable as an identifier once you get to the neighborhood and very often only once you get to the street.”

I like Conor's distinction between house number and house address.  It's true there are many houses with the number 15, thus the house number is a local identiier, and only becomes universal when combined with the street name, the city, and so on.  I hadn't understood that this is what he was trying to say.

Then Conor continues:

“I will admit that there are some differences with the MAC address because of how basic Ethernet networking was designed. The MAC address is designed to be unique (though, those in networking know that this isn't always the case and in fact most devices let you override the mac address anytime you want). So this could be claimed to be some form of a universal identifier. However, it's not at all usable outside of the local neighborhood. There is no way for me to talk to a particular MAC address unless I am locally on the same network with that device.”

Conor is completely right here.  In networking as we have known it, the MAC address is not usable outside the “local network neighborhood”.  But that is exactly what this WiFi snooping is about to change.  In fact this is very much the core of what I'm talking about.

MAC addresses will be used to reveal where you live

Once you have snooped peoples’ MAC addresses, and put them into a database linking them to “where they live” (literally),  you have dramatically changed the way network identifiers work.

In this new world, armed with such a database, if you see a MAC address somewhere – anywhere – you can look it up in your database – precisely because it is unique – and see where “it lives”.   When I say, “where it lives”, I don't mean what network it belongs to.  I mean where it is normally located in physical space – as a street address.  

Is there some way to opt out of this?  No – other than turning everything off.  Unfortunately, given the way networks are designed, we have no choice but to reveal our MAC address when we use our Wireless.  So  anyone who is physically near us and has access to a linking database has access to where we live. I'll explore the implications of this going forward.

Conor concludes,

“I do believe that a more privacy enabled design of networking would have allowed for scenarios where MAC addresses were more dynamic and thus reducing the universal-ness and persistence of the MAC address itself…”

We both agree on this.  And IPV6 has plenty of options that could make this possible.  However, the current infrastructure is the one we live in, and one which is sorely in need of protections, mores and regulations.  The fact that current technology allows the creation of Dr. No technology like that which Google StreetView WiFi has laid on the world doesn't mean that society should or will.



Are SSIDs and MAC addresses like house numbers?

Architect Conor Cahill writes:

Kim's assertion that Google was wrong to do so is based upon two primary factors:

  • Google intended to capture the SSID and MAC address of the access points
  • SSIDs and MAC addresses are persistent identifiers

And it seems that this has at least gotten Ben re-thinking his assertion that this was all about privacy theater and even him giving Kim a get-out-of-jail-free card.

While I agree that Kim's asserted facts are true, I disagree with his conclusion.

  • I don't believe Google did anything wrong in collecting SSIDs and MAC addresses (capturing data, perhaps). The SSIDs were configured to *broadcast* (to make something known widely). However, SSIDs and MAC addresses are local identifiers more like house numbers. They identify entities within the local wireless network and are generally not re-transmitted beyond that wireless network.
  • I don't believe that what they did had an impact on the user's privacy. As I pointed out above, it's like capturing house numbers and associating them with a location. That, in itself, has little to do with the user's privacy unless something else associates the location with the user…

Let's think about this.  Are SSIDs and MAC addresses like house numbers?

Your house number is used – by anyone in the world who wants to find it – to get to your house.  Your house was given a number for that purpose.  The people who live in the houses like this.  They actually run out and buy little house number things, and nail them up on the side of their houses, to advertise clearly what number they are.

So let's see:

  1. Are SSIDS and MAC addresses used by anyone in the world to get through to your network?  No.  A DNS name would be used for that.  In residential neighborhoods, you employ a SSID for only one reason – to make it easier to get wireless working for members of your family and their visitors.  Your intent is for the wireless access point's MAC address to be used only by your family's devices, and the MACs of their devices only by the other devices in the house.
  2. Were SSIDS and MAC addressed invented to allow anyone in the world to find the devices in your house?   No, nothing like that.  The MAC is used only within the confines of the local network segment.
  3. Do people consciously try to advertise their SSIDs and MAC addresses to the world by running to the store, buying them, and nailing them to their metaphorical porches?  Nope again.  Zero analogy.

So what is similar?  Nothing. 

That's because house addresses are what, in Law Four of the Laws of Identity, were called “universal identifiers”, while SSIDs and MAC addresses are what were called “unidirectional identifiers” – meaning that they were intended to be constrained to use in a single context. 

Keeping “unidirectional identifiers” private to their context is essential for privacy.  And let me be clear: I'm not refering only to the privacy of individuals, but also that of enterprises, governments and organizations.  Protecting unidirectional identifiers is essential for building a secure and trustworthy Internet.


TERENA Networking Conference and the Fourth Law

I gave a plenary keynote on the Laws of Identity to the TERENA conference in Vilnius this week.  The intense controversy around Google's world mapping of private WiFi identifiers made it pretty clear that the Fourth Law of Identity is not an academic exercise.  TERENA is a place where people “collaborate, innovate and share knowledge in order to foster the development of Internet technology, infrastructure and services to be used by the research and education community.”

People in the identity community will have heard me talk about the Laws of Identity before. However it was refreshing to discuss their implications with people who are world experts on networking issues.  [Humanitarian hint:  don't blow up the video or you'll not only miss the sides but become very conscious that I had several cups of good Vilnius coffee before getting up on stage.]